Electrical condenser



Maly 6, 1930. s. s. CRAMER ET Al. 1,757,357

ELECTRICAL coNDENsER Filed Dec. 6, 41926 capacity of one' condenser unit with respect,

Patented May 6, 1930r PATENT oFF STANLEY S. CRAMER, OF HADDON HEIGHTS AND RUSSELL E. CRAMER, F AUD'UBON, NEW JERSEY, ASSIGNORS T0 RADIO CONDECBISER COMPANY, 0F CAMDEN, NEW

JERSEY ELECTRICAL CONDENSER i Application led December 6, 1926. Serial No. 152,786.

This invention relates to an electrical condenser of the variable type, and is especially adapted for use in connection with wireless sending and receiving sets in which tunable circuits are used.

It .is the object of our invention tol provide an electrical condenser of a construction which will give a capacity curve of a predetermined character.

In the operation of many radio receiving sets it is quite customary to build the loud speaker as a part of the set, and in other cases, the loud speaker is many times placed close to, or even on top of the receiving set,

and in either of the cases mentioned, the vibration set up by the loud speaker is transmitted more or less strongly to' the plates, especially those of the rotor of the tuning eondensers and these vibrations set up objectionable sounds that are picked up and transmitted by the amplifying tubes in the set.

It is therefore another object of our invention to provide means for eliminating these sympathetic vibrations in the tuning condensers.

A further object of our invention is to provide al construction which is generally strong mechanically. and one that is comparatively simple and easy to make.

Another object of our invention is to provide compensating means Jfor balancing the to another,- particularly where these units are used in tandem for single dial control for a plurality of units.

rlhese and other objects of our invention will be apparent, after a study of the speciiication taken in connection with the annexed drawing, wherein:

Figure 1, is an end view looking at the operating end of the condenser, with the rotor lin disengaged or zero position of the operating dial.

Figure 2 is a rear end view of the condenser but with the rotor in full engaged position,y

with the stator.

Figure 3 is a front view of the condenser with the stator and rotor in the sameposition as shown in Figure 2.

Figure 4 is a view of the rear end plate looking from the inside.

Figure 5 is a view of the operating shaft.

Figure 6 is" a section through the rotor on the line 6-6 Lof Figure 1. ,Y l i Figure 7 is a plan view of one of the rotor plates, while Figure 8 is a plan view of one of the stator plates. A

In the drawing, wherein like numbers refer to corresponding parts in the various views: 1 is a Jfront end plate and 2 a rear end plate, which support the condenser parts. Each of the plates areprovided with lugs 3 and 4, which preferably project inwardly and each of which is provided with a hole 5, to receive screws 6, used for liolding the insulating strips 7 and 8 in position. The end plates 1. and 2 are further connected together by the studs 9 and 10, which are preferably staked into the end plate 1, as shown 1nr Figurel 1 and fastened by screws tol the end plate 2, as shown in Figure 2. p

Each of the stator plates 11 as shown in Figure, 8, has'three extensions 12, 13 and 14, which are outside the active part of the plate as engaged by the rotor plates. -Each of these extensions are provided with notches 15, so formed .as to leave ears 16 and 17 on opposite sides of the notch 15. A rectangular shaped metal plate 18 having slots therein, is

adapted to fit in the notch 15, so that the slots in the plate 18 closely vengage the ears 16 which are, after the plate has been put in position, preferably ,upset so as to securely anchor the stator plate to the anchor plate 18.

The anchor plate 18 is provided with a pair of holes-19, which are threaded to receive screws 20, fastened through the insulating strip 7,v thereby supporting the stator group of pilates, between the end plates 1 and 2, and the insulating strips 7 and 8.

As will be understood from Figures2 and 8, the anchor plates for supporting ,the stator directly, are op ositely disposed one with respect to the ot er, while the third anchor plate 18, is intermediate the first two anchor plates as shown in Figure 2, and may be termed a floating anchor. TheI rotor plate 2l shown in Figure 7 is preferably in the shape of a truncated pear, and has an leXtension 22, somewhat similar to extensions 12, 13 and 14, but preferably somewhat longer. This extension 22 is provided with a similar notch 15 and ears 16, and 17 ,and a supplemental notch 23.

An anchor plate 18 serves to anchor the rotor plates 21 securely together, as has been described with respect to the stator plates,

thus it will be seen that one style of anchor plate serves for both the stator and the rotor.

Mounted within the supplemental notch 23 is an insulating strip 24 (shown in Figure 6) which acts as a stop for the rotor when "the same is turned into full engagement position, as shown in Figure 2.

The insulator 24 being adapted to engage the'stator plates, each of the rotor plates 21 is provided with a projection 25, which are adapted to engage the insulating strip .8 (see Figure l) thereby actingoas a stop for the rotor when the dial is turned to the zero position.

Therotor plates21 are also provided with a boss 26 which has holes or perforations 27, to receive the shaft portion 28. Asthe rotor plates are mounted on the shaft L28 they butt against the collar 29, and are separated from each other by a suitable spacingcollar. The shaft preferably has a flat portion 30, associated with the threaded part 31, to receive at least one special rotor plate having a flat portion as indicated by the dotted line 47 (see Figure 7) thereby providing a lock in connection with the clamp nut 32. Each of the end plates has a projection 48 on one side and extending above the stator plates and lying to one side of a verticallcentral plane through the condenser and the end plate lis provided with a threaded bushingv33, which is preferably non-movably held in the plate 1, by any suitable means such as swedging the metal of the platel around the end of the bushing 33, as shown in Figure 1. The bushing 33 is formed with a tapered seat adapted to receive the taper portion 34 of the operating shaft. `The opposite end of the shaft is provided with a tapered portion 35, t0 fit. into a corresponding taper in the bushing 36, carried in the end plate 2. The bushing 36 is provided with a screw slot 37 ,.so that it may be quickly adjustedagainst 4the seat 35, and locked into position by a lock nut 38. The end plate 2, has fastened thereto a brake member 39 inthe form of a spring which has an opening 40, which 'preferably is a clearance hole for the end of the operating shaft.l f

The spring 39 applies pressure against the nut 32, comprising part of the rotor unit,so that the rotor unit is held in any position in which it may be set by the operating dial. While I have shown the member 39 as completely encircling the operating shaft, it is"V` medium df the screws 20, or one or both of the plates 18 may be constructed so that the terminal is integral therewith.

When our condenser stator and rotor units are used in tandem for single dial control, the shaft portion 28, is simply made longer, andlikewise the insulating strips 7 and 8, as

lwell as the spacing studs 9 and 10. The rest of the parts remain the same.

When the condenser is arranged in tandem, we may use a compensating member in the form of a disc 45', which is carried on the stud 46, whereby the compensating disc 45 may be adjusted toward or away from its stator unit thereby varying the capacity of the same slightly so as to bring each condenser and its associated coil into electrical balance. A In some cases similar results may be obtained by reversing one of the end plates l or 2, whereby it will be assembled'so the lugs 3 and 4 project outwardly instead of in- Wardl as shown in the drawing, thus bringing t e end plate relatively close to the rotor and stator plates, thus giving an inherent shielding due to the plate itself.

It is to be understood that the details of our invention may be varied considerably, without departing from the spirit of our invention and the scope of the appended claims.

Having thus described our invention, what we claim is:

1 "A variable condenser comprising; a group offstator plates having at least two fixed anchorages, and a floating anchorage (intermediate the fiXed anchorages, a group of rotor plates each having a projecting boss a shaft passing through a hole in the boss of each plate and a floating anchorage for said rotor plates, disposed arcuately thereof a distance measured on the shortest arc, less than half the arcuate length of the rotor plate, but so as to permit full cooperation between said rotor and stator.

2; A. variable electrical condenser comprising; a group of stator plates, and a cooperating group of rotor plates, said stator plates each having three extensions with sets of notches formed therein so as to provide ears on opposite sides of the notches, plates having slots therein tofit over said ears and resting in said notches, one pair of said plates being oppositely disposed and adapted to be fas- ECL tened to theosu-pport member, said third plate beinfr positioned between and below said pair of plates, said rotor plates each having an extension with notches therein similarly to erating Ygroup of rotor plates, said stator plates each having three extensions with sets of notches formed therein so as to provide ears on opposite sides of the notches, plates having slots therein to lit over said ears and resting in said notches, one pair `of said plates being oppositely disposed and adapted to be fastened to support member, said third plate beinr ositioned between and below said pair of plates, and said rotor plates each having an extension with notches therein similarly to the stator plateso, and a supplemental notch, a similarly formed and mounted plate anchoring the rotor plates in proper spaced relationship, a stop insulator mounted below said anchor plate in said supplemental notch, and an operating `shaft anchoring and carrying the rotor plates at a,

oint distant from said anchor plate, less than lialf the arcuate length of a rotor plate.

4. A variable electrical condenser comprising, a pair of end plates each having a pair of lugs, an insulator joining and fastened to each pair ofl lugs, a groupvof stator plates anchored to oppositely disposed bridge members, means for fastenin said bridge members to the insulators, a t ird bridge member fastened to the stator plates, intermediate and below the first two mentioned bridge members and independent of the end plate a rotor consisting of agroup of lates rotatably supported between said en plates, and a bridge member -anchoring the rotor plates as and for the purpose described.

5. A variable electrical condenser comprising, a pair of end plates, each havin a pair of luo's, an insulator joining and astened to eac pair of lugs, a group of stator plates anchored to oppositely disposed bridge members, means for fastening said bridge members to the insulators, a third bridge member fastened to the stator plates intermediate and below the first two mentioned bridge members; a rotor consisting of a group of plates rotatably supported between said end plates, a bridge member similar to those used on the stator anchoring said rotor plates together at a point arcuately spaced-from the rotor support, less than one half the arcuate length of a rotorilate, a full operative stop insulator carrie by the rotor lates beneath its bridge member and a projection on each of said stator plates for engaging one ofsaid first mentioned insulators thereby forming a stop for the rotor. when moved to, `nonoperative position.

6. A variable electrical condenser comprising; a pair of end plates each having a pair of lugs, an insulator joining and fastened to each pair of lugs, a group of stator plates,

`anchored too positely disposed bridge members, means or fastening said bridge inembers to the insulators, a third bridge member fastened to the stator plates intermediate and below the first two mentioned bridge members and .independent of the end plate, a rotor consisting of a group of plates rotatably supported between said end plates, and a bridge member anchoring. the rotor plates as and for the purpose described, all of said bridge members consisting of slotted recntangular plates resting in notches in the plates said stator and rotor plates having ears on opposite sides of the notches to engage said slots in the bridge members.

7. A variable electrical condenser comprising; a pair of end plates each having a pair of lugs, an insulator joining and fastened to each pair of lugs, a group of stator plates anchored to oppositely disposed bridge members, means for fastening said bridge member to the insulators, a third bridge member fastened to the stator plates intermediate` and abelow the first two mentioned bridge members, a rotor consisting of a group ofl plates rotatably supported between said end plates, said rotatable support comprising; bushings screw threaded into said end plates, at least one bushing-being adjustable, said bushings having tapered seats and a shaft having a collar against which" said rotor plates are pressed by a nut engaging a threaded portion of the shaft, said shaft having tapered parts adjacent the collar and the threadedportion forfitting the tapered seats in said collars, a brake spring carried by an end plate and extending over said shaft and pressing against the rotor structure to hold the same in any set position and a bridge member anchoring the rotor plates at a point from the shaft not exceeding one half the arcuate length of a rotor disc. l

8. A variableelectrical condenser comprising; a group of stator plates and a cooperating 1group of rotor plates said stator plates oppositely disposed and adapted to be fasj A tened to support member said third plate being positioned between and below said pair of plates, said rotor plates having a shapeY like a truncated pear with a perforated boss at the truncated end and a notched .projection oneach plate, located near the small diameter, an anchor plate fastened to said notched lend plates for carrying said support members and for rotatably vcarrying said shaft.

9. A variable electrical condenser compris- 4 ing, a frame work having a pair of end plates fastenedy together in spaced relation, an insulating strip on opposite sides of the condenser and extending between the end plates,

a group ofstator plates fastened to oppositely disposed metal anchor pieces, said yanch'or pieces'being fastened to said insulating strips, said end plates having bosses projecting above said stator plates and to one side of a vertical plane through the center of the condenser, a rotor shaft carried by said bosses and a group of truncated pear shaped rotor plates eachI having a perforated boss on the truncated end to fit on said shaft.

10. A variable electrical condenser comprising, a frame work having a pair of end plates fastenedtogether in spaced relation, an insulating strip on opposite sides of the condenser and 'extending between the end plates, a group of stator plates fastened to oppositely disposed metal anchor pieces, said anchor pieces being fastened to said insulating strips, said end plates having bosses projecting above said stator plates and to one side of a vertical plane through the center of the condenser, a rotor shaft carried by said bosses and a group of truncated pear shaped rotor plates each having a perforated boss.

at the truncatedend to lit on said shaft, said stator plates having an anchor plate intermediate said first two anchor plates while said rotor has a similar anchor plate arran ed on the rotor plates in a position to allow ull cooperative engagement with the stator.

ll. In a variable electrical condenser, a pair of end plates, eachliaving a pair of lugs, insulation members extending between the end plates and fastened tisaid lugs, a pair of oppositely disposed bridge members, a group of stator plates anchored to the said oppositely disposed bridge members, means for fastening said bridge members to the insulation members; a rotor consisting of a group of plates rotatably supported between Said end plates, la bridge member similar to tures.

tions `for 'said rotor, said means in one position of the rotor comprising a part of the condenser frame, and the other position of-said rotor comprising a member made of insulating material on said rotor adapted to engage the stator.

13. A variable condenser comprising a frame having a pair of end plates and connecting spacer elementswa stator insulatably mounted on said frame, a rotor mounted in said frame and conductively connected thereto and means providing stop or limiting positions of' said rotor, said means comprising one of said spacer elements in one position of said rotor andkcomprising for the other position of said rotor a strip of insulating material arranged at the circumference of the rotor and adapted to engage with the stator.

In testimony whereof, we aiif fw-z" signa- STANLEY S. omi/inn. RUSSELL E. cnannn.

those used on the stator set anchoring said rotor plates together at a point areuately spaced from the'rotor support, less than one half the arcuate length of a rotor plate. An insulator strip carried by the rotor plates beneath its bridge member adapted to engage a portion of said stator plates to form a stop for 

